It is known to fit the rear window opening of a truck cab with a sliding window assembly made up of a pair of stationary window panes mounted outboard in a window opening to define an gap therebetween, and one or two window sliding panes retained along their upper and lower edges in guide tracks for horizontal movement between open and closed positions. Many different power window regulator mechanisms have been proposed to allow an occupant of the truck to open and close the sliding window by actuating a switch. These prior art regulator mechanisms generally employ a reversible electric motor to drive a rack-and-pinion mechanism or a flexible, inextensible drive member such as a cable or a slotted tape to move the sliding panes between the open and closed positions.
In many prior art sliding window regulators, a guide track or rail extends parallel to the path of movement of the sliding pane and one or more carrier plates are slidingly engaged with the guide rail and are moved back and forth therealong by one or more flexible drive members. The carrier plates typically make a rigid connection with the sliding pane so that any movement of the pane perpendicular to the direction of sliding movement and any tipping of the pane is transferred directly to the carrier plates, and vice versa. The rigid connection between the carrier plates and the pane may tend to cause binding problems when the track in which the sliding pane travels is not perfectly flat and parallel with the guide track for the carrier plates. U.S. patent application Ser. No. 09/126,649, assigned to the assignee of the present patent application, discloses a window regulator in which a pane carrier engages a sliding pane by means of a sliding male/female connection which restrains the sliding pane against tipping and binding within its guide track yet allows relative movement between the pane carrier and the sliding pane along an axis perpendicular to the pane. This type of connection allows the regulator to operate properly, without binding or jamming, when attached to a window assembly that is not perfectly flat along the direction of sliding movement. It also simplifies the assembly process, since the regulator does not have to be attached to the window assembly with a great deal of precision.
The prior art power sliding window regulators have also generally required a relatively high degree of dimensional accuracy in the window assembly, the regulator, and the interface between these two assemblies. This is a consequence of the drive components of the regulator mechanism being integrated with the window frame and/or guide rails for the sliding panes. In a relatively new type of automotive vehicle window assembly, known as a "frameless" assembly, the fixed window panes are installed directly into the window opening to provide a more simple and clean appearance. Since there is no rigid frame surrounding the window panes, the dimensional accuracy and "flatness" of such an assembly depends upon the construction of the vehicle structure surrounding the window opening. Because of normal manufacturing tolerances, the surrounding structure is likely to be less dimensionally precise than a traditional, separately fabricated window frame.
Several known regulators employ a pull/pull drive system, wherein the drive member is routed so that it is placed in tension and applies a pulling force to the sliding pane to move it in both the opening and closing directions. Such a pull/pull drive configuration allows the cables to be constructed to less exacting dimensional tolerances than would be the case if the cable were placed in compression to push the pane in one of the directions, with a resulting reduction in cost. Pulling the pane also greatly eliminates friction due to binding of the cables and the sliding pane that would be present if a pushing force were applied, thereby allowing the use of a substantially smaller, less powerful and less expensive motor.
One method of achieving a pull/pull drive configuration is taught by U.S. Pat. No. 5,531,046 in which a linear actuator is connected to a sliding pane at two points adjacent the lower, outboard corners of the sliding pane. This allows the single linear actuator to apply the pulling force to the leading lower edge of the pane as it slides in both directions. This design uses two separate carrier plates attached to the sliding pane adjacent opposite lower corners and which slide independently along the guide rail.
U.S. Pat. No. 5,822,922 discloses a regulator which achieves a pull/pull configuration utilizing elongated glass attachments which are secured to the sliding pane along its entire lower edge. While this achieves the desired pull/pull configuration, the glass attachments are rigidly mounted to the sliding pane. The glass attachment also constitutes the guide plate, being engaged with the guide track along its entire length. While this configuration achieves the desired pull/pull configuration, it does not allow any out-of-plane relative movement between the pane and the glass attachment/carrier plate.